Electric eurnace



June 15 1926. 1,588,520

' E. J. BRANNEGAN ELECTRIC FURNACE Filed April- 29 1924 WITNESSES: vINVENTOR Ed v d J. Bmrmi cm.

.M I; g

ATTORNEY Patented June 15, 1926.

UNITED STATES 1 1,588,520 PATENT OFFICE."

EDWARD J. BRANNIGAN, OF IBUFFALO, NEW YORK, ASSIGNORTO'WESTING-I-IOIJ'SE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OFPENNSYLVANIA. I

ELECTRIC FURNACE.

Application filed April 29, 1924. Serial No. 709,729.

My invention relates to electric furnaces and particularly toelectric-resistance furnaces having carbonaceous heating units.

The object of my invention is to provide a quickly removableheating-unit aggregate for a high-temperature furnace.

In practicing my invention, I provide a plurality of refractory wallsenclosin a furnace chamber andlocate within the urnace chamber ahigh-back tray having relatively low side and end walls, within whichtray is located a refractory heating element. A suitable opening isprovided in one of the furnace walls, normally closed by a suitableclosure member against which the high-back end of the tray is pressed bysuitable elongated terminal electrodesthat are resiliently pressedagainst the outer ends of the built up parts of theplural-resistormember.

It has been found, in actual practice, that the use of refractoryresistor members comprising some form of carbonaceous elements isnecessary, if it is desired to obtain a relatively high operatingtemperature within a furnace chamber. A certain amount of oxidation ofthese resistor members takes place during the operation of the furnace,making it necessary to replace the heating units from time to time. Ifit is necessary to partially disassemble the furnace structure in orderto replace such a heating unit, a relatively large amount of time islost, and it is highly desirable to provide a furnace structure and aheating unit that will permit of easy and quick removal of a damagedheating unit and of the quick insertion of a new heating unit, wherebythe furnace is out of operation only a relatively short time.

In the single sheet of drawings Figure 1 is a view, partially inhorizontal section and partially in plan, of an electric resistancefurnace embodying my invention, and

Fig. 2 is a view, in vertical lateral section therethrough, taken on theline 11-11 of Fig. 1. I

A furnace 11 comprises an outer metallic casing 12 of any suitable ordesired contour and dimensions that is supported by a plurality ofsupporting members 13 which may either be integral with the casing ormay be suitably secured thereagainst in any desired manner.

An outer lining 14 comprises a plurality 16 of any suitable or desiredcontour and dimensions. 7

The furnace chamber 16'may be divided into two compartments, an upperorworkreceiving compartment 17 and a lower or heating-compartment 18, bya refractory diaphragm 19 that may comprise carbon,

graphite or similar material that will withstand the relatively. hightemperatures encountered in the operation of the furnace without seriousdeterioration or oxidation thereof.

One of the walls of the furnace is provided with an opening 21, near thebottom 7 of the furnace'chamber 16, that may be substantiallyrectangular in section and that may also be of wedge shape in order topermit of locating therein a. closure member 22, of refractory material,that is also of wedge shape, whereby a close engagement between thebricks or blocks of the furnace structure immediately surrounding theopening 21 and the closure member 22 may be obtained.

The closure member 22 may be suitably secured against the inner surfaceof a metal plate 23 that is provided with a plurality of handles 24 and25 to permit of an operator handling the same in its removal from, andits insertion into the opening 21.

Means for securing the closure member 22 together with the plate 28 intheir proper operative positions comprise a clamping bolt 26 and aclamping member 27, of U-shape that has a turning movement on the bolt26. One end of the clamping member 27 operatively engages the furnacecasing while the other operatively engages a portion of the plate 28, asuitable tightening means 28 operatively engaging the outerscrew-threaded end of the bolt 26. The tightening means 28 is hereillustrated as a butterfly nut but may, of course, be of any othersuitable or desired construction as long as it is effective to tightlyhold the closure member22 and the plate 23 in their properoperativepositions, substantially as illustrated in the drawings.

A heating unit for the furnace comprises a tray 29 that has threerelatively low side and end portions and a high backfil and that iscomposed of a suitable refractory high-temperature-resisting andelectricinsulating material. lVithin the tray 29 I provide an elongatedbar 32 of a suitable electric-conducting refractory material that isspaced from the high back 31 by a plurality of blocks 33, 34; and 35, ofa suitable electricinsulating refractory material.

A plurality of relatively thin plates 36 are located in adjacent andface-to-face relation at each of the ends of the bar 32 and extend fromthe inner face thereof to within a short distance of the other end ofthe tray Where a pair of terminal blocks 37 and 38 are located, inoperative engagement with the respective end plates of each group ofplates 36. I

A pair of elongated electric-conducting terminal electrodes 39 and 411project into the furnace chamber, extending through openings 42 and 43in that wall of the furnace structure opposite the opening 21. Theelectrodes 39 and 11 are located a suitable distance apart in ordertohave the inner ends thereof engage the blocks 37 and 38, respectively.

lVater cooled terminal members 14i. and 4-5 operatively engage the outertapering ends of the respective elongated electrodes and a block 46, ofa suitable refractory material, such as asbestos lumber, is located atthe surface of the furnace structure and is provided with two openings47 and 48, respectively, within which the terminal members 1 1 and 45are located. The block 46 insures not only the alinement of theelectrodes and the terminal members, but also prevents leakage ofcurrent therefrom during the operation of the furnace.

Means for resiliently pressing the terminal members and the terminalholders against the several portions of the built-up resistor membercomprise screw-threaded rods 49 and 51, the outer ends of which arsuitably held in fixed members 52 and that may be of L-shape, asillustrated more particularly in Fig. 2 of the drawing, and have one endthereof suitably secured against the metal casing 12. Helical springmembers 5 1 and 55 surround a portion of the rods 19 and 51,respectively, and press against washers 56 and 5?, the outer surfaces ofwhich operatively engage nuts 58 and 59, respectively, that are mountedon the rods 49 and 51.

The inner ends of the respective rods 19 and 51 may be enlarged and mayoperatively engage plates 61 and 62 of a suitable electric-insulatingmaterial, that are located against the outer surface of the respectiveterminal members 1 1 and 45.

\Vhile I have illustrated a specific embodiment of resilient compressingmeans, I do not desire to be limited thereto, as the constructiondescribed is illustrative only and any construction providing resilientcompressing means may be employed.

In assembling the furnace structure and particularly in mounting theheating unit comprising the stacks of plates 36 in the tray 29, theclosure member 22 is removed and the tray, together with the resistormember, is inserted in the furnace structure through the opening 21 intosubstantially the position illustrated more particularly in Fig. 2 ofthe drawings.

it is assumed that the elongated refractory electrodes are already inposition and when the tray, together with the resistor members, is movedinto its proper operative position, the terminal blocks 37 and 38 willbe caused to operatively engage the inner ends of the electrodes.

The closure member 22, together with the plate 23, is then placed in itsproper operative position and clamped therein by the clamping bolt 26and the cooperating tightening means 28. The nuts 58 and are nowtightened against the springs 54 and 55, respectively, thereby causingthe elongated electrodes to be resiliently pressed against the portionsof the resistor memher. The resistor member may be energized by suitablesupply cireuit conductors (not shown) that are electrically connected tothe terminal members te'l and 4:5 in the usual manner.

When the oxidation of some or all of the resistors has proceeded to suchextent as to make it impossible to use them any longer, and it isdesired to remove the heating unit, it is only necessary to discontinueenergization of the resistor member and to slackcn the nuts 58 and 59.The closure member 22 is then removed and the tray 29, together with theresistor, as hereinbefore described, located therein, is then removed, apair of spaced projections (33 and (i l being provided on each side ofthe tray 29 at the higlrbrck end thereof to permit of a suitable pullingtool. being employed to move the tray outwardly through the opening 21.If desired, a layer of granular material or a plate (35 of a suitableelectric-insulating refractory material, may be located at the bottom ofthe heating compartment 18 in order to permit of the easy insertion andremoval of the tray, as hereinbefore described.

Whereas, in furnaces employing other ty es-of heating units, it wasnecessary to disassemble at least a portion thereof before a damagedheating unit could be removed and a new one substituted therefor, whichrequired that the furnace structure be permitted to cool. It is notnecessary to do this in the device embodying my invention, wherein it isonly necessary to remove lltl art.

movable into and out of said through said opening, a plurality of spacedthe closure member after which the heating unit may be easily andquickly removed and another one inserted within a very short time, whichmay then be energized after completing the reassembly of the furnacestructure, as hereinbefore described.

Various modifications'and changes may be made without departing from thespirit and scope of the invention. I desire therefore that only suchlimitations shall be placed thereon as are imposed by the prior I claimas my invention 1. In an electric resistance furnace, the combinationwith a plurality of refractory walls enclosing a furnace chamber andhaving an opening in one wall thereof and a removable, refractoryclosure member for said opening, of a refractory tray, movable into andout of said chamber, through said opening, and a refractory resistormember located in said tray.

2. In an electric resistance furnace, the combination with a pluralityof refractory walls enclosing a furnaceichamber, and aresiliently-mounted electrode in one of said walls, of a relativelyshallow tray in said chamber and a resistor member in said tray havingone end thereof in operative engagement with said electrode.

3. In an electric resistance furnace, the combination with .a pluralityof refractory walls enclosing a furnace chamber having an opening in onewall thereof at the bottom of the chamber, a movable refractory closuremember for said opening, and a resiliently mounted terminal electrode inone of said walls opposite said opening, of a refractory tray, and arefractory resistor member in said tray, movable into and out of saidchamber through said opening and the resistor member held in operativeengagement with said electrode by said closure member.

4. In an electric resistance furnace, the combination with a pluralityof refractory walls enclosing a furnace chamber having an opening in oneWall thereof, a. removable refractory closure member for said opening,and a plurality of resiliently-mounted elongated terminal electrodesprojecting into the furnace chamber, of a high-back tray of refractoryelectric-insulating material chamber parallel-extending resistor memberslocated in said tray and having one end of each operatively engaging thehigh-back of the tray and having the other end of each held in operativeengagement with the inner ends of the electrodes.

5. In an electric resistance furnace, the combination with a pluralityof refractory walls enclosing a furnace chamber and having an opening inone wall thereof, of a removable heating unit aggregate movable into andout of said chamber through said opening, said aggregate comprising arelatively shallow tray of refractory electricinsulating material, and atwo-part refractory resistor member located in said tray, a refractoryclosure member for said opening abutting one end of said tray, and apair of elongated terminal electrodes projecting into the furnacechamber opposite to said opening and operatively engaging the resistormember.

6. In an electric resistance furnace, the combination with a pluralityof refractory walls enclosing a furnace chamber and having an opening inone wall thereof, of a quickly removable heating unit aggregate normallylocated in said chamber, and com prising a shallow tray of refractoryelectricinsulating material and a plurality of refractory electricconducting plates located on edge in said tray and projecting above theupper edges thereof.

7. In an electric resistance furnace, the combination with a pluralityof refractory walls enclosing a furnace chamber having an opening in oneWall thereof, and a refractory closure member for said opening, of aquickly removable heating unit aggregate movable into and out of saidchamber through said opening and comprising a high-baok shallow tray ofrefractory electric-insulating material, and a pair of resistor elementslocated therein and comprising a plurality of electric-conductingrefractory plates standing on edge and projecting above the top of saidtray, and a pair of terminal electrodes projecting into said chamber andresiliently pressed against the ends of the resistor elements.

In testimony whereof, I have hereunto subscribed my name this 16th dayof April EDWARD J. BRANNIGAN

